January 2005 Chemistry Regents #11-20

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

 

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Questions

Answer Explanations
11 Which compound contains both ionic and covalent
bonds?
(1) CaCO3    (3) MgF2
(2) PCl3           (4) CH2O
1 look for 3 elements and one must be a metal
12 Which formula represents a nonpolar molecule?
(1) HCl         (3) NH3
(2) H2O        (4) CF4
4 draw it. It is symmetrical
13 When a lithium atom forms an Li+ ion, the lithium atom
(1) gains a proton
(2) gains an electron
(3) loses a proton
(4) loses an electron
4 becomes positive by losing an electron
2 3 valence electrons

2-3

15 A sample is prepared by completely dissolving 10.0 grams of NaCl in 1.0 liter of H2O. Which classification best describes this sample?
(1) homogeneous compound
(2) homogeneous mixture
(3) heterogeneous compound
(4) heterogeneous mixture
2 solutions are homogenous mixtures
16 Which form of energy is converted to thermal energy when propane burns in air?
(1) electromagnetic           (3) electrical
(2) nuclear                        (4) chemical
4 chemical comes from bonds
17 Which physical changes are endothermic?
(1) melting and freezing
(2) melting and evaporating
(3) condensation and sublimation
(4) condensation and deposition
2   

energy goes in

18 Which transfer of energy occurs when ice cubes are placed in water that has a temperature of 45C?
(1) Chemical energy is transferred from the ice to the water.
(2) Chemical energy is transferred from the water to the ice.
(3) Thermal energy is transferred from the ice to the water.
(4) Thermal energy is transferred from the water to the ice.
4 heat is thermal and goes from hot to cold
19 At STP, 4 liters of O2 contains the same total number of molecules as
(1) 1 L of NH3        (3) 8 L of He
(2) 2 L of Cl2          (4) 4 L of CO2
4 Avagodros Hypothesis-equal vol. of gas contain equal numbers of molecules
20 What is the total number of electron pairs that are shared between the two carbon atoms in a molecule of ethyne?
(1) 1            (3) 3
(2) 2            (4) 4
3 3 there is a triple bond

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

 
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